I. Field of the Invention
The present invention relates to a system and to a method for controlling the temperature of a fuel cell system mounted on board a motor vehicle.
II. Description of Related Art
Controlling the temperature of the fuel cell is important to prevent the cell from overheating as this could lead to damage to the cell.
Standard fuel cells of the PEM (Proton Exchange Membrane) type comprise elemental individual cells which are made up in particular of a bipolar plate and of a Membrane Electrodes Assembly, or MEA for short. These are the solid elements of the fuel cell.
A fuel cell also comprises fluid elements including the products obtained by the electrochemical reactions that take place within the fuel cell in order to supply the electrical energy. Such a cell is supplied with hydrogen at the anode, for example by a reformer, and with oxygen at the cathode, generally by an air compressor unit.
Systems for controlling the temperature of a fuel cell do exist.
Documents U.S. Pat. No. 4,640,873, FR 2 809 535 and JP 9 213357 relate to systems for the temperature control of a fuel cell in which systems the temperature of the cell is assimilated to the temperature of the fluid elements.
However, there is a discrepancy between the temperature of the solid elements of the cell and of the fluid elements of the cell, and this leads to temperature control of limited effectiveness because it is based on the temperature of the fluid elements rather than on the temperature of the solid elements.